Views 3 : how to display distinct nodes

Hello,

I've fill in the "distinct" option in query settings but it doesn't work... Does anyone have a solution ?
Here's my view export for the country content type :

$view = new view;
$view->name = 'wd_country_list';
$view->description = 'List of content type country ';
$view->tag = '';
$view->base_table = 'node';
$view->human_name = 'worldwide directory';
$view->core = 6;
$view->api_version = '3.0-alpha1';
$view->disabled = FALSE; /* Edit this to true to make a default view disabled initially */

/* Display: Defaults */
$handler = $view->new_display('default', 'Defaults', 'default');
$handler->display->display_options['access']['type'] = 'none';
$handler->display->display_options['cache']['type'] = 'none';
$handler->display->display_options['query']['type'] = 'views_query';
$handler->display->display_options['query']['options']['distinct'] = TRUE;
$handler->display->display_options['exposed_form']['type'] = 'basic';
$handler->display->display_options['pager']['type'] = 'none';
$handler->display->display_options['pager']['options']['offset'] = '0';
$handler->display->display_options['style_plugin'] = 'default';
$handler->display->display_options['style_options']['grouping'] = 'field_continent_nid';
$handler->display->display_options['row_plugin'] = 'fields';
/* Field: Content: Country (field_country) */
$handler->display->display_options['fields']['field_country_nid']['id'] = 'field_country_nid';
$handler->display->display_options['fields']['field_country_nid']['table'] = 'node_data_field_country';
$handler->display->display_options['fields']['field_country_nid']['field'] = 'field_country_nid';
$handler->display->display_options['fields']['field_country_nid']['alter']['alter_text'] = 0;
$handler->display->display_options['fields']['field_country_nid']['alter']['make_link'] = 0;
$handler->display->display_options['fields']['field_country_nid']['alter']['absolute'] = 0;
$handler->display->display_options['fields']['field_country_nid']['alter']['external'] = 0;
$handler->display->display_options['fields']['field_country_nid']['alter']['replace_spaces'] = 0;
$handler->display->display_options['fields']['field_country_nid']['alter']['trim'] = 0;
$handler->display->display_options['fields']['field_country_nid']['alter']['nl2br'] = 0;
$handler->display->display_options['fields']['field_country_nid']['alter']['word_boundary'] = 1;
$handler->display->display_options['fields']['field_country_nid']['alter']['ellipsis'] = 1;
$handler->display->display_options['fields']['field_country_nid']['alter']['strip_tags'] = 0;
$handler->display->display_options['fields']['field_country_nid']['alter']['html'] = 0;
$handler->display->display_options['fields']['field_country_nid']['element_type'] = '0';
$handler->display->display_options['fields']['field_country_nid']['element_label_colon'] = 1;
$handler->display->display_options['fields']['field_country_nid']['element_default_classes'] = 1;
$handler->display->display_options['fields']['field_country_nid']['hide_empty'] = 0;
$handler->display->display_options['fields']['field_country_nid']['empty_zero'] = 0;
$handler->display->display_options['fields']['field_country_nid']['link_to_node'] = 0;
$handler->display->display_options['fields']['field_country_nid']['label_type'] = 'none';
$handler->display->display_options['fields']['field_country_nid']['format'] = 'plain';
/* Field: Content: Continent (field_continent) */
$handler->display->display_options['fields']['field_continent_nid']['id'] = 'field_continent_nid';
$handler->display->display_options['fields']['field_continent_nid']['table'] = 'node_data_field_continent';
$handler->display->display_options['fields']['field_continent_nid']['field'] = 'field_continent_nid';
$handler->display->display_options['fields']['field_continent_nid']['exclude'] = TRUE;
$handler->display->display_options['fields']['field_continent_nid']['alter']['alter_text'] = 0;
$handler->display->display_options['fields']['field_continent_nid']['alter']['make_link'] = 0;
$handler->display->display_options['fields']['field_continent_nid']['alter']['absolute'] = 0;
$handler->display->display_options['fields']['field_continent_nid']['alter']['external'] = 0;
$handler->display->display_options['fields']['field_continent_nid']['alter']['replace_spaces'] = 0;
$handler->display->display_options['fields']['field_continent_nid']['alter']['trim'] = 0;
$handler->display->display_options['fields']['field_continent_nid']['alter']['nl2br'] = 0;
$handler->display->display_options['fields']['field_continent_nid']['alter']['word_boundary'] = 1;
$handler->display->display_options['fields']['field_continent_nid']['alter']['ellipsis'] = 1;
$handler->display->display_options['fields']['field_continent_nid']['alter']['strip_tags'] = 0;
$handler->display->display_options['fields']['field_continent_nid']['alter']['html'] = 0;
$handler->display->display_options['fields']['field_continent_nid']['element_label_colon'] = 1;
$handler->display->display_options['fields']['field_continent_nid']['element_default_classes'] = 1;
$handler->display->display_options['fields']['field_continent_nid']['hide_empty'] = 0;
$handler->display->display_options['fields']['field_continent_nid']['empty_zero'] = 0;
$handler->display->display_options['fields']['field_continent_nid']['link_to_node'] = 0;
$handler->display->display_options['fields']['field_continent_nid']['label_type'] = 'none';
$handler->display->display_options['fields']['field_continent_nid']['format'] = 'plain';
/* Filter: Node: Type */
$handler->display->display_options['filters']['type']['id'] = 'type';
$handler->display->display_options['filters']['type']['table'] = 'node';
$handler->display->display_options['filters']['type']['field'] = 'type';
$handler->display->display_options['filters']['type']['value'] = array(
'country_office_info' => 'country_office_info',
);
/* Filter: Node translation: Langue */
$handler->display->display_options['filters']['language']['id'] = 'language';
$handler->display->display_options['filters']['language']['table'] = 'node';
$handler->display->display_options['filters']['language']['field'] = 'language';
$handler->display->display_options['filters']['language']['value'] = array(
'***CURRENT_LANGUAGE***' => '***CURRENT_LANGUAGE***',
);

/* Display: Block */
$handler = $view->new_display('block', 'Block', 'block_1');
$translatables['wd_country_list'] = array(
t('Defaults'),
t('more'),
t('Apply'),
t('Reset'),
t('Sort by'),
t('Asc'),
t('Desc'),
t('Block'),
);